Of course hot rock geothermal should be a significant part of the mix and it's good to hear that work continues.

But, strictly speaking, it should not be described as renewable. The rate of radioactive heating and up-welling energy from deep down is so slow that what one is actually doing is 'mining' a resource of heat. Extracting the hot water cools the rocks, eventually to the point where you have to give up. Still, in the right locations, that could take a very worthwhile length of time._________________http://biffvernon.blogspot.co.uk/

The article isn't behind a pay wall, but you might have to register to read it.

It's another from of nuclear in this case, as the radioactive granite decomposes it releases heat. Some geothermal heat comes from fault lines which allow water up from great depths where the heat is of volcanic origin.

Southampton city centre gets some of its heat from geothermal pumping._________________As Steve Keen puts it: â€śCapital without energy is a statue; labour without energy is a corpse.â€ť Economics ignores this which is why economics is broken.

.....But, strictly speaking, it should not be described as renewable. The rate of radioactive heating and up-welling energy from deep down is so slow that what one is actually doing is 'mining' a resource of heat. Extracting the hot water cools the rocks, eventually to the point where you have to give up. Still, in the right locations, that could take a very worthwhile length of time.

It would be renewable if the rate of extraction of heat matched the rate of production and dissemination.

With this sort of geothermal set up two boreholes are often drilled and the rate of production depends on the porosity of the rock between the two holes. This is because water is pumped down one hole, through the hot rock and up the other. Modern fracking and horizontal drilling methods could increase the efficiency of this system._________________As Steve Keen puts it: â€śCapital without energy is a statue; labour without energy is a corpse.â€ť Economics ignores this which is why economics is broken.

There's no reason why it couldn't, apart from, possibly, human greed. If the temperature of the water started dropping just reduce the flow rate until it picks up again._________________As Steve Keen puts it: â€śCapital without energy is a statue; labour without energy is a corpse.â€ť Economics ignores this which is why economics is broken.

I think it's like sucking water out of a swimming pool with a straw - it will run out, but slowly, very slowly because there is a tap dripping into the pool.

With some hot rock geothermal it's actually quick enough to make it not worthwhile. In other places there's no bother. Heat flow rates are critical. I'm just pointing out that, strictly speaking, geothermal is not 'renewable'. One is mining a resource, though in some places the resource is very large._________________http://biffvernon.blogspot.co.uk/

The problem would be if we sucked so much heat out of the core that it solidified causing the earth to lose its magnetic field. That, in turn, would cause the loss of much of our atmosphere. We would have to go at geothermal pretty hard to do that though._________________As Steve Keen puts it: â€śCapital without energy is a statue; labour without energy is a corpse.â€ť Economics ignores this which is why economics is broken.

The deepest borehole (exploratory not geothermal) has only reached 0.2% of the way to the centre of the Earth so I guess it'll be a while before we achieve the heat death of the planet. _________________http://biffvernon.blogspot.co.uk/

Beware the power of exponential growth!!_________________As Steve Keen puts it: â€śCapital without energy is a statue; labour without energy is a corpse.â€ť Economics ignores this which is why economics is broken.

I agree about the geothermal is not renewable point. My friend has a website that deals with like geothermal energy and he keeps writing renewable energy sources, yet I am inclined to believe that just because something hasn't been proven as non-renewable, there is also a complete lack of evidence to support the former. If that makes any sense.

Consequently, I'd also be inclined to believe that drawing energy from hot rocks with such slow speed of heat generation could prove rather insignificant, if not useless. Yet it is good they are trying to explore more options._________________"It seems that every time mankind is given a lot of energy, we go out and wreck something with it."
David R. Brower